Since a phonebook and reception/transmission mail addresses are stored in a mobile phone usually and accessed to be referred to or to be changed, there is a possibility that such information is read by a third person and personal information or the like are leaked when the mobile phone is lost. To deal with such problems, a phonebook management system in which phonebook data and the like are uploaded into a server provided in a network of a wireless provider, to be downloaded according to a request from the mobile phone side as necessary has been proposed (Patent Document 1).
Also, there has been proposed a data access device with which the phonebook data and the like are uploaded in a server, and when the data is transferred and displayed on the mobile phone, confidential information is stored in a volatile memory and general information is stored in a non-volatile memory, so that the confidential information is not remained in the mobile phone once the power is off (Patent Document 2). Further, a mobile phone configured such that dial lock or data erasing can be performed from a radio base station, even after the mobile phone is lost, has been also proposed (Patent Document 3).    Patent Document 1: Japanese Patent Application Laid-Open No. 2002-57807    Patent Document 2: Japanese Patent Application Laid-Open No. 2003-223368    Patent Document 3: Japanese Patent Application Laid-Open No. 2003-319453